1. Technical Field
The present invention is directed to determining an arrival time of passengers boarding an elevator car. More particularly, the present invention is directed to determining an arrival time for each of the passengers boarding an elevator car.
As used herein, the term "arrival time" means the time at which a passenger arrives at an elevator, or the area in which the elevators are located, for service in a predetermined direction.
2. Background Information
In a building having a plurality of floors, each floor typically has a set of buttons located in the hallway at or near the elevator(s). These buttons, commonly referred to as hall call buttons, allow a user to request elevator car service in-a predetermined direction, e.g., up or down. Additionally, the interior of an elevator car is generally equipped with a plurality of buttons, commonly referred to as car call buttons, which allow users to request service to specific floors.
In simplified terms, an elevator control system, also referred to in the art as a dispatching system, monitors the status of the hall call buttons at the floors and car call buttons in the elevators, dispatching an elevator car to the floors in response to hall call and/or car call button registration. The door on the arriving elevator car opens, allowing passengers to board and/or deboard the car at the floor, and then closes.
Elevator dispatching systems for controlling the assignment of elevator cars in a building are well known in the art. In some of these systems, historic information regarding passenger traffic flow is recorded and used to predict future traffic patterns, yielding more efficient service. See, e.g., U.S. Pat. Nos. 4,838,384, 4,846,311 5,022,497 and 5,024,295 all to the same inventors, and owned by the same assignee, as the present invention, herein incorporated by reference.
In such prior an systems having traffic prediction, passenger traffic flow, e.g., the number of passengers boarding an elevator at a floor in response to a hall call, is typically determined for a plurality of time intervals, typically 3 to 5 minutes each. Passenger traffic flow data collected during these time intervals over the course of a specific day, as well as over a plurality of days preceding the specific day, is used to predict the traffic flow.
The change in the elevator car load due to passengers boarding and deboarding is determined and converted into passenger boarding counts. Alternatively, passenger boarding counts are determined by a people sensing/counting arrangement. See, e.g., U.S. Pat. No. 4,799,243 issued to Zepke and assigned to the same assignee as the present invention. In the prior art, the passenger boarding counts are associated with the time interval during which the elevator car doors closed.
As known in the art, the time delay between hall call registration and an elevator car's arrival in response to the hall call is a function of several factors, e.g., traffic conditions, the number of elevators in service, the dispatching algorithm utilized, and en route delays caused by intermediary hall calls and/or car calls. Because of this time delay, it is possible that passengers will register a hall call during one time interval but will be serviced by an elevator car during a subsequent time interval. In these situations, prior art systems which group all boarded passengers in the time interval during which the elevator door is closed inaccurately portray passenger arrival times.
By associating passenger boarding counts with the time interval during which the elevator car door is closed, passengers appear to arrive in groups, at the time when the elevator car door is closed. Because passengers arrive in a more distributed fashion over the time period between hall call registration and when the elevator car door is closed, predictions based on group passenger arrival when the elevator car door closes are inherently inaccurate.